Reactors for torrefaction of biomass have been proposed in a variety of configurations. Most include some type of machinery which moves or manipulates the biomass so as to expose the mass to a flowing stream of hot gases. Such devices have been identified in US 2012/0085023, which describes a rotating drum heated by an internal gas stream. DE 102010045612 describes a horizontal cylinder with an internal conveyor with external heating. WO2011135305 describes a reactor wherein hot gases are injected at high velocity into a toroidal bed of biomass, and US 20120073159 describes a modified tray drier with internal circulation of hot gases to conduct the torrefaction of biomass. All of these devices require a mechanical device of some significant horsepower to move either the biomass or the hot gases. While all of the processes are conducted at near atmospheric pressure, there is a slight positive pressure and thus the potential for leakage exists of the torrefaction gases, especially at rotating shafts and external duct work. In addition, the scale-up of these devices is limited by the long residence time required to conduct the torrefaction reaction. The manifestation of these issues results in process equipments which are quite large; require large horsepower motors to move the biomass and/or the hot gases; and which contribute to an overall undue complexity. Accordingly there is a need to present a torrefaction system which mitigates these issues.